Sexual Mimicry in the Animal Kingdom

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Finding a mate in the animal kingdom is no easy feat. There’s a tonne of competition, and if animals want to stand a chance of breeding, they need to make sure they stand out from the crowd.

While there are lots of ways that animals do this, sexual mimicry is pretty common. This is when a creature imitates behaviors or pheromones of other animals, including those of the opposite sex within their own species. The idea is that their chances of successfully mating are boosted.

This is a fascinating phenomenon that happens in many ways and across many species. In this article, we’ll be exploring some of the ways that various animals do this and why it’s so effective.

What is Sexual Mimicry?

While most common in invertebrate species, sexual mimicry is something that’s seen across the animal kingdom. For example, both the garter snake and spotted hyena employ this interesting mating tactic.

Sexual mimicry is a strategy whereby some animals imitate the chemical signals, behavior, or even appearance of a member of the opposite sex. In some cases, they’ll even mimic another species, all in the hope of getting a mate.

But it’s not just done to ensure successful breeding. Some animals will even use sexual mimicry to lessen the competition from more dominant members of the species and even as a form of self-defense.

In the main, there are two types of sexual mimicry; interspecific and intraspecific. Intraspecific sexual mimicry refers to the phenomenon taking place between two members of the same species. When this happens, either the male or the female will take on characteristics of the opposite gender.

While we might associate this behavior with animals, it also occurs in plants, such as certain orchid species. This is known as interspecific sexual mimicry, as the plant mimics the appearance or behavior of another species; quite commonly, an insect.

So, how does this work? Well, some species of orchid, like the bee orchid, appear to have a bee sitting on the petals. But it’s not an insect; it’s actually part of the plant! Bees are attracted to this and head to the plant to investigate. However, there’s nothing there for them but in the process, they get covered in orchid pollen and this ensures successful pollination of the plant. Sneaky but clever!

This is a form of sexual mimicry known as visual mimicry because the plant is taking on the appearance of its target. But this isn’t the only form. Chemical mimicry occurs when an animal imitates the pheromones given off by the opposite sex, whereas acoustic mimicry sees an animal reproducing the sounds of the opposite sex to increase their chances of mating.

Advantages of Sexual Mimicry

For humans, it might be difficult to understand how exactly mimicking a member of the opposite sex would result in successful mating. But in the animal kingdom, it’s a tactic that has been proven to work time and time again.

The most obvious advantage is more mating opportunities. This works because by looking like a female, this can confuse other males within the area, meaning that the she-male gets more chances with the real females. This is something we see in garter snakes which mate in large competitive balls.

What’s more, it’s been observed that by imitating the appearance of a female, males stand less chance of being met with aggression by other males. This, therefore, eliminates competition when looking for a mate and is something that is observed in spotted hyenas. 

Another great benefit of sexual mimicry is mate selection. The females of some species, such as the damselfly, take on the appearance of a male. This prevents her from being harassed by determined males and gives her a much greater choice of who she mates with.

Intraspecific Sexual Mimicry Among Animals

Intraspecific sexual mimicry is something we see in a lot of animal species. From fish in the ocean to insects and even some types of mammals and reptiles, it’s going on everywhere!

1. Giant Cuttlefish

The giant cuttlefish is found off the eastern coast of Australia and these tricksters have some of the most impressive sexual mimicry strategies in the ocean.

They employ a form of visual mimicry whereby a male can appear as both female and male at once. When he spots a potential mate, he may be met with competition from another male. So, instead of wasting his energy in a fight, he places himself between the object of his affection and his competition. 

On one side of his body, he’ll display a mottled pattern similar to that of the female. This throws his competitor off the scent. While on the other side of his body, he flashes a mating display at the same time as passing sperm parcels to the female. He’s literally mating with her in plain sight but the competition is blissfully unaware.

And it’s a good job that these creatures are able to use this trickery since around 70% of all males are rejected during mating efforts owing to a serious female:male ratio imbalance.

2. Photuris Firefly

There is a species of firefly known as the big dipper and they are able to produce a chemical known as lucibufagins which acts as a defense against predators. While the photuris firefly is larger, it isn’t able to produce such chemicals but it does have a sneaky way of getting hold of them.

The female of the species is able to imitate the flashes of the female big dipper and this attracts a male’s attention. When he approaches, he’ll release those chemicals but, because of his naivety, is soon gobbled up by the photuris female. However, he does have a defense against this in the form of a sticky substance that clogs up the female’s jaws. So, she needs to be quick if she’s going to reap the rewards of her imitations.

In this case, it’s less about finding a mate and more about being able to survive!

3. Bluegill Sunfish

Within the males of the bluegill sunfish there are dominant breeders and not so dominant breeders. The dominant males, known as parentals, are much more aggressive in their mating and have the greatest success. In fact, it’s even been shown in studies that their sperm is much more dense and has greater longevity.

On the other hand, there are cuckolders who are not as dominant and, compared to the parentals, stand very little chance of successfully mating. But in order to level the playing field, they use a few alternative mating strategies including female mimicry.

So convincing is the appearance of the male in terms of looking like a girl that a dominant male in the process of wooing a true female won’t bat an eyelid. This trickery gives the less dominant male the chance to swoop in and deposit his sperm.

4. Garter Snakes

After six months of hibernation, male garter snakes are forced directly into a race to breed. Tens of males will emerge at the same time and start warming up in anticipation of the first female coming out of hibernation. But when she does, the competition really heats up as she’ll only mate with one male.

Any males that are out of the big twisted ball near the female wouldn’t stand a chance. But sexual mimicry saves the day as these males release a pheromone scent that’s just like that of the female. This serves as a distraction technique for the other males who will leave the cluster to investigate.

When they do this, they’ll warm him up which allows him to get in on the action near the female and gives him a much higher chance of success. 

5. Cicadas

If you’re a cicada, then the best way to find a mate is to sing. When I say sing, I mean use your tymbal organ located on your abdomen; if you’re a male, that is. When males use this organ to make a chirruping sound, it’s usually met with a responsive click from an interested female. 

However, scientists have now discovered that male cicadas are also able to produce this clicking sound and they do it to eliminate competition.

In a form of acoustic sexual mimicry, males will respond to the chirruping calls of other males on the lookout for love. When these males start coming closer, the trickster will grab them and attack them by clamping their jaws around their heads.

6. Spotted Hyena

For female spotted hyenas, the process of giving birth is one of the most traumatic in the animal kingdom. So, it’ll come as no surprise that she’s fussy about who she mates with. But she’s also fussy about which other females mate with the males in the pride.

There’s usually only one dominant female, and unlike a lot of other species, it’s the females that mimic the males. Female hyenas have an enlarged clitoris that looks strikingly like a penis, which is why it’s often referred to as a pseudopenis. 

This appendage is thought to have initially evolved as a way of fooling other hyenas into believing she’s a male which reduces the risk of aggression from dominant females. However, behaviors around mating have also been observed and females will invite males to lick their pseudopenis so they can determine that she’s actually female and go ahead with the process of mating.

7. Ruff

The ruff is a species of wading bird, and the males may have one of three different appearances. Like many bird species, when it comes to mating, males will gather in groups called leks. Within these groups, they will perform rituals to attract a female, but in the case of the ruff, there’s only one type of dominant male.

These males are showy and have elaborate tufts, and within a lek, as many as 95% may have this appearance; they’re known as independents. However, there are smaller satellite males as well as a very small handful of faeders who look just like females.

Because of this appearance, the faeders are able to move freely among more dominant males in the lek and avoid aggression. All the while, on the lookout for a true female with which to sneakily mate. While the independents are busy fighting off competition, the faeders go largely unnoticed.

8. Broadley’s Flat Lizard

You’d think it would be highly beneficial to look like a female in order to avoid aggression from other males. In many cases, this is true but with Broadley’s flat lizard, there is a catch. While some males do have an appearance similar to that of the female, they’re not able to mimic their scent.

What this essentially means is that these she-males can wander freely through male territory to look for a mate without drawing too much attention to themselves. However, if another male gets too close, he will be able to smell the she-male’s scent, and his cover will be blown. 

In studies, it has been shown that males use their tongues to detect the pheromones given off by females. One group of researchers labeled she-males with a male scent and this seemed to be enough to convince other males who tried to mate with them.

9. Damselflies

With most animals that perform sexual mimicry, it’s the males that are the tricksters but that isn’t the case with the damselfly. The females of this species have evolved over time to look more like males.

The obvious benefit of this is that any given female can avoid the pursuits of a determined male and this gives her freedom of choice about whom she mates with. It’s pretty advantageous for this species since the males are known for their aggression when it comes to pursuing a female.

One of the most common forms of this visual sexual mimicry can be seen when females take on the coloration of their male counterparts. These are known as andromorph females but it isn’t something that they’re all capable of. In fact, many females, known as gynomorphs continue to possess the more drab coloration which will attract the attention of a male.

10. Marsh Harrier

Marsh harriers are a species of raptor and the largest within the harrier family. However, the females tend to be much larger than the males, so visual sexual mimicry certainly comes in handy, and it’s estimated that as many as 40% of all males have a more feminine appearance.

It’s believed that these males take on the appearance of a female in order to eliminate aggression from other males. But what’s really interesting is that they aren’t born this way and typically start looking more girly in the second year of life.

When this happens, their plumage changes to be more like the brown color of the females. That said, their size doesn’t change, and males typically have smaller eyes; since these features don’t change, it’s still possible to tell a male from a female if you look closely enough.

But even in the event that these mimics are still attacked by other males, studies have shown that they still respond in a manner that would suggest they really believe they are female. Talk about embracing your role!

11. Cotesia rubecula

Cotesia rubecula is a type of parasitic wasp that uses a mating tactic called mate guarding. This is just one form of sexual mimicry and is used to prevent others of the same species from attempting to breed with an individual’s mate.

In order to attract a mate, these wasps will use a couple of tactics; they’ll emit a pheromone as well as create vibrations to draw the attention of a female. If she’s receptive, she will assume a responsive position and copulation can occur.

However, once one male has mated with her, he doesn’t want anyone else giving it a go so he’ll hang around for a while. In the event that another male makes any attempts, it will be the first male that adopts the receptive position, throwing the intruder off the scent and confusing him.

12. Dark-Edged Splitfin

Found in the mountainous regions of Mexico, the dark-edged splitfin is a type of cold-water fish. What’s interesting is that sexual mimicry begins early in this fish’s life, with juvenile males mimicking pregnant adult females, thanks to a spot located near the vent. It’s been shown that these spots become more prominent after losing a fight with another male. 

How might this be beneficial? Well, the primary reason for this visual mimicry is to prevent aggressive attacks from other males. However, this isn’t the only advantage of looking like a girl.

Since older, more dominant males usually have the greatest access to females, looking like a female allows these juveniles to get closer, thereby increasing their chances of actually mating. This is super important because females have a very small breeding window of just five days!

13. White-Necked Jacobin Hummingbird

The white-necked Jacobin hummingbird is a species of tropical hummingbird, and the males have impressive plumage with a green back and deep blue head. However, the females are much less showy; but not in all cases.

Some female white-necked hummingbirds have been known to take on the appearance of their male counterparts. In fact, research has shown that as many as 30% of all females could be crossdressers and this is largely done to avoid being harassed by a determined male looking for a mate. It’s also been noted that females with male coloration tend to have better access to food sources than their drab sisters. 

Typically, female white-necked Jacobin hummingbirds are born with bright feathers, but these usually fade. When they’re young, this benefits them from being harassed when they’re at their most vulnerable.